I would think that Danielle was not kidnapped while it was just her father in the home. He would have heard Westfield. It is more likely that she was snatched while everyone was home and in the garage, high, and making noise. They would have been oblivious as to what was going on in the home if they were locked in the party garage.
Prolly right....I should have mentioned that the neighbor, in order to execute his plan, needed to know if the wife was accompanied by her husband. Once he discovered she was not, had to wait until they collectively engaged in the "festivities" in the garage before acting.
Since he may have been seen on his trip to the bar, he probably made an overt effort to be recognized by Mrs. Van Dam, which led to the comment about dancing with her. Obviously this guy is a pervert of a different nature. But, it seems to me that the parent's activities enabled him to pull this off on the evening of 2/2 and no one is going to call the Van Dams to task that their behavior, the sex or the drugs might have led to their daughter's death.